The complaint charges that at Boston on September 1, 1948, the defendant "did wilfully and unreasonably saunter and loiter in a certain public street ... called Columbus Avenue for more than seven minutes after being then lawfully directed there ... to move on" by a police officer. In the Superior Court the defendant waived trial by jury, and was tried, convicted, and sentenced to pay a fine of $20. The judge, being of opinion that there is involved a question of law so important or doubtful as to require the decision of this court, with the consent of the defendant, reported the case, and stayed proceedings. G.L. (Ter. Ed.) c. 278, § 30.

In the view we take, the facts are unimportant. The part of the ordinance here considered we hold to be void on its face as repugnant to the due process clause of § 1 of the Fourteenth Amendment to the Constitution of the United States and to art. 12 of the Declaration of Rights of the Constitution of this Commonwealth. It undertakes to make criminal an intentional and unreasonable failure by one on a street to move on as soon as seven minutes have elapsed after a direction to that end given by a police officer. Prima facie, mere sauntering or loitering on a public way is lawful and the right of any man, woman, or child. This the Commonwealth concedes. Under the ordinance, such conduct continues conditionally lawful subject to a direction to move on by a police officer followed by unreasonable failure to comply and the expiration of seven minutes. Not all idling is prohibited, but only that which is unreasonable. The vice of the ordinance lies in its failure to prescribe any standard capable of intelligent human evaluation to enable one chargeable with its violation to discover those conditions which convert conduct which is prima facie lawful into that which is criminal. A "statute which either forbids or requires the doing of an act in terms so vague that men of common intelligence must necessarily guess at its meaning and differ as to its application, violates the first essential of due process of law." Connally v. General Construction Co. 269 U.S. 385, 391. Lanzetta v. New Jersey, 306 U.S. 451, 453. Winters v. New York, 333 U.S. 507, 515-516. Commonwealth v. Slome, 321 Mass. 713, 715. And this is no less true of a municipal ordinance or regulation. Druzik v. Board of Health of Haverhill, 324 Mass. 129, 133-134.

The broad sweep of this enactment is unnecessary to the suppression of disorder or even of congestion in the streets, evils at which legislation may be aimed in appropriately direct *522 language without affording a locus poenitentiae of seven or any other number of minutes.